The charming, heartwarming drama has taken Britain (and our period drama-loving cousins across the pond) by storm since it first premiered on BBC1 in 2012. It was an unlikely hit – who’d have thought births, babies and nuns would make millions of us sit down in front of our telly sets – but there’s no denying it is one. And with a successful Christmas special under their belt and a third series currently in production, Poplar’s birthing nuns are definitely here to stay.

So what do you need to know? Based on the memoirs of real life midwife Jennifer Worth, Call the Midwife is set in the 1950s (1957 to be exact). But you can push all thoughts of Grease to the back of your mind – it’s more post-war poverty than polka dots (don’t worry though, there are still polka dots…)

The first episode kicks off by introducing 22-year-old Jenny – a newly qualified midwife who’s been sent out into the big bad world to start her first job. She arrives in the East End of London, finding herself out of place in the busy, brash and poverty-stricken district, to embark on a career at working convent Nonnatus House. And that’s where the magic begins…

It’s not always an easy watch – from prostitution and abortion to neglect and newborn fatalities, there is more to Call the Midwife than schmaltz and soppy sentiment – but as soon as Vanessa Redgrave utters her first soothing syllable, you’ll be hooked. Add a couple of bicycle bells and a fifties floral dress and you’ll be in period drama heaven. (I promise.)